- Hydrogenation catalysts based on platinum- and palladium-containing nanodiamonds
-
Platinum and palladium nanoparticles of 4-5 nm size applied at nanodiamonds have been shown to efficiently catalyze liquid-phase hydrogenation of different organic compounds (nitrocompounds, azomethines, and unsaturated hydrocarbons and alcohols) under mild conditions (T = 318 K, hydrogen pressure of 0.1 MPa, solution in ethanol). Using of palladium on nanodiamond containing 3 wt % of metal has been most efficient.
- Magdalinova,Kalmykov,Klyuev
-
-
Read Online
- Hydrogenation of unsaturated compounds in the presence of palladium-containing modified carbon nanofibers
-
Palladium-containing carboxylated carbon nanofibers were studied as catalysts for hydrogenation of double bond >C=C in olefins, unsaturated alcohols, and acids, as well as for hydrogenation of nitroarenes. The developed catalyst is 7 times more efficient than the industrial analog (Pd/C).
- Osipov,Klyuev
-
-
Read Online
- Preparation of highly active heterogeneous Au@Pd bimetallic catalyst using plant tannin grafted collagen fiber as the matrix
-
Au@Pd bimetallic nanoparticles (NPs) catalysts were synthesized by a seeding growth method using bayberry tannin grafted collagen fiber (BT-CF) as the matrix. In this method, Au3+ was first reductively adsorbed onto BT-CF to form Au NPs, and then they serve as the seeds for the over growth of Pd shell. The morphology of BT-CF-Au@Pd catalyst was observed by TEM and SEM, and the core-shell structure of the Au@Pd was confirmed by EDS and XRD. It was found that the as-prepared BT-CF-Au9@Pd3 catalyst showed excellent synergy effect in liquid-phase hydrogenation of cyclohexene, whose reaction time was three times faster than that catalyzed by BT-CF-Pd catalyst under the same conditions. Meanwhile, the BT-CF-Au9@Pd3 catalyst could be re-used four times without significant loss of activity. In the fourth run, the substrate conversion was still as high as 92.70%, much better than that by using commercial Pd/C catalyst (42.60%). Additionally, BT-CF-Au9@Pd3 catalyst exhibited high hydrogenation activity to various alkenes and nitro-compounds. For example, the TOF of allyl alcohol, styrene and nitrobenzene hydrogenations reached 10,980, 14,732 and 1379 mol mol-1 h-1, respectively.
- Ma, Jun,Huang, Xin,Liao, Xuepin,Shi, Bi
-
-
Read Online
- An Innovative Approach for Highly Selective Direct Conversion of CO2into Propanol using C2H4and H2
-
Multifunctional catalysts are developed for converting CO2with C2H4and H2into propanol. Au nanoparticles (NP) supported on TiO2are found to facilitate this reaction. The activity and selectivity strongly depend on NP size, which can be tuned by the method of Au deposition and by promoting with K. The promoter improves the selectivity to propanol. Under optimized reaction conditions (2 MPa, 473 K, and CO2/H2/C2H4=1:1:1), CO2is continuously converted into propanol with a near-to-100 % selectivity. Catalytic tests as well as mechanistic studies by in situ FTIR and temporal analysis of products with isotopic tracers allow the overall reaction scheme to be determined. Propanol is formed through a sequence of reactions starting with reverse water–gas shift to reduce CO2to CO, which is further consumed in the hydroformylation of ethylene to propanal. The latter is finally hydrogenated to propanol, while propanol hydrogenation to propane is suppressed.
- Ahlers, Stefan J.,Bentrup, Ursula,Linke, David,Kondratenko, Evgenii V.
-
-
Read Online
- Pd nanoparticles immobilized on boehmite by using tannic acid as structure-directing agent and stabilizer: A high performance catalyst for hydrogenation of olefins
-
Boehmite-supported Pd nanoparticles (Pd-TA-boehmite) were successfully synthesized by a hydrothermal method using tannic acid as the structure-directing agent as well as stabilizer. The physicochemical properties of the Pd-TA-boehmite catalyst were well characterized by XPS, XRD, N 2 adsorption/desorption, and TEM analyses. Catalytic hydrogenation of olefins was used as the probe reaction to evaluate the activity of the Pd-TA-boehmite catalyst. For comparison, the Pd-boehmite catalyst prepared without tannic acid was also employed for olefin hydrogenation. For all the investigated substrates, the Pd-TA-boehmite catalyst exhibited superior catalytic performance than the Pd-boehmite catalyst. For the example of hydrogenation of allyl alcohol, the initial hydrogenation rate and selectivity of the Pd-TA-boehmite catalyst were 23,520 mol/mol h and 99 %, respectively, while those of the Pd-boehmite catalyst were only 14,186 mol/mol h and 93 %, respectively. Additionally, the hydrogenation rate of the Pd-TA-boehmite catalyst could still reach 20,791 mol/mol h at the 7th cycle, which was much higher than that of the Pd-boehmite catalyst (5,250 mol/mol h) at the 4th cycle, thus showing an improved reusability.
- Liu, Jing,Liao, Xuepin,Shi, Bi
-
-
Read Online
- Hydrogenation of Propoinaldehyde by Nickel Catalysts Supported on Al2O3, SiO2, TiO2, Ta2O5, and Nb2O5
-
The hydrogenation of propionaldehyde with various nickel catalysts was studied kinetically for a wide range of reaction conditions.The catalysts were supported on Al2O3, SiO2, TiO2, Ta2O5, and Nb2O5.The reaction rates were well correlated with the irreversibly adsorbed hydrogen uptakes.A detailed analysis concluded that this reaction was structure-insensitive under all reaction conditions tested.
- Funakoshi, Masaki,Inoue, Hakuaki
-
-
Read Online
- Solvent Effects in the Homogeneous Catalytic Reduction of Propionaldehyde with Aluminium Isopropoxide Catalyst: New Insights from PFG NMR and NMR Relaxation Studies
-
Solvent effects in homogeneous catalysis are known to affect catalytic activity. Whilst these effects are often described using qualitative features, such as Kamlet-Taft parameters, experimental tools able to quantify and reveal in more depth such effects have remained unexplored. In this work, PFG NMR diffusion and T1 relaxation measurements have been carried out to probe solvent effects in the homogeneous catalytic reduction of propionaldehyde to 1-propanol in the presence of aluminium isopropoxide catalyst. Using data on diffusion coefficients it was possible to estimate trends in aggregation of different solvents. The results show that solvents with a high hydrogen-bond accepting ability, such as ethers, tend to form larger aggregates, which slow down the molecular dynamics of aldehyde molecules, as also suggested by T1 measurements, and preventing their access to the catalytic sites, which results in the observed decrease of catalytic activity. Conversely, weakly interacting solvents, such as alkanes, do not lead to the formation of such aggregates, hence allowing easy access of the aldehyde molecules to the catalytic sites, resulting in higher catalytic activity. The work reported here is a clear example on how combining traditional catalyst screening in homogeneous catalysis with NMR diffusion and relaxation time measurements can lead to new physico-chemical insights into such systems by providing data able to quantify aggregation phenomena and molecular dynamics.
- Muhammad, Atika,Di Carmine, Graziano,Forster, Luke,D'Agostino, Carmine
-
-
Read Online
- Highly efficient hydrogenation of methyl propionate to propanol over hydrous zirconia supported ruthenium
-
Hydrous zirconia supported ruthenium catalyst Ru/ZrO2? xH2O, prepared by co-precipitating ruthenium trichloride and zirconium oxychloride with ammonia, was able to catalyze efficiently methyl propionate to propanol under the mild conditions. In aqueous system, the propanol yield of >99% was achieved under the conditions of reaction temperature of 150 °C and hydrogen pressure of 5.0 MPa, while in non-aqueous system the maximum propanol yield was only 47.0%. FTIR spectra and hydrogenation results indicated that the high catalytic performance of Ru/ZrO2?xH2O in aqueous phase results from the cooperation effect between water as a solvent and hydroxyl groups on the surface of carrier.
- Fan, Guangyin,Zhou, Yafen,Fu, Haiyan,Ye, Xiaoli,Li, Ruixiang,Chen, Hua,Li, Xianjun
-
-
Read Online
- Palladium-containing nanodiamonds in hydrogenation and hydroamination
-
Palladium catalysts in the form of Pd nanoparticles supported on nanodiamonds have been studied in the hydrogenation of nitrobenzene, allyl alcohol, and cyclohexene and in the hydrogenating amination of propanal with 4-aminobenzoic acid. The ratio of two valence states of palladium, i.e., Pd 2+ and Pd0, in the catalysts has been determined by XPS. The dependence of hydrogenation reaction rate on electron density at the reaction site of nitrobenzene, allyl alcohol, cyclohexene, and 4-(propylideneamino)benzoic acid molecules has been studied using quantum chemical calculations (HF/6-31G, PCM). Pleiades Publishing, Ltd., 2012.
- Magdalinova,Kalmykov,Klyuev
-
-
Read Online
- Sulphonated "click" dendrimer-stabilized palladium nanoparticles as highly efficient catalysts for olefin hydrogenation and Suzuki coupling reactions under ambient conditions in aqueous media
-
Water-soluble 1,2,3-triazolyl dendrimers were synthesized by "click chemistry" and used to stabilize palladium nanoparticles (PdNPs). These new "click" dendrimer-stabilized nanoparticles (DSN) are highly stable to air and moisture and are catalytically active for olefin hydrogenation and Suzuki coupling reaction, in aqueous media, under ambient conditions using a low amount of palladium (0.01 mol% Pd). Kinetic studies show high catalytic efficiency and high stability for the new "click" DSN in both reactions. The complexation of potassium tetrachloropalladate (K 2PdCl4) to the triazole ligands present in the dendritic structures was monitored by UV/vis and, after reduction, the nanoparticles were characterized by transmission electron microscopy (TEM).
- Ornelas, Catia,Ruiz, Jaime,Salmon, Lionel,Astruc, Didier
-
-
Read Online
- Efficient hydrogenation of methyl propionate over bnehmite-Supported Ru-Pt catalyst
-
The bimetallic catalyst Ru-Pt/AlOOH exhibited good catalytic performance in water for the hydrogenation of methyl propionate to 1-propanol. The selectivity to 1-propanol of 97.8% was obtained with a conversion of 89.1% at 453 K, 5MPa for 6 h. The incorporation of Pt for the improvement of the catalystic activity was attributed to promoting the reduction of Ru3+ to Ru0. Copyright
- Zhou, Ya-Fen,Wei, Juan,Fan, Guang-Yin,Fu, Hai-Yan,Li, Rui-Xiang,Chen, Hua,Li, Xian-Jun
-
-
Read Online
- Pt-And Pd-containing nanodiamonds in hydrogenation and hydroamination reactions1
-
The catalytic activity of platinum-And palladium-containing nanodiamonds has been investi-gated in liquid-phase nitrobenzene, allyl alcohol, and cyclohexene hydrogenation and propanal hydroami-nation with 4-Aminobenzoic acid as model reactions. The catalysts suggested are significantly more active than commercial Pd/C. The catalysts with a low metal weight content are the most effective in liquid phase catalytic hydrogenation. Pleiades Publishing, Ltd., 2012.
- Magdalinova,Klyuev,Vershinin,Efimov
-
-
Read Online
- Towards the upgrading of fermentation broths to advanced biofuels: A water tolerant catalyst for the conversion of ethanol to isobutanol
-
Isobutanol is an ideal gasoline replacement due to its high energy density, suitable octane number and compatibility with current engine technology. It can be formed by the Guerbet reaction in which (bio)ethanol and methanol mixtures are converted to this higher alcohol in the presence of a suitable catalyst under basic conditions. A possible limitation of this process is the catalyst's water tolerance; a twofold problem given that water is produced as a by-product of the Guerbet reaction but also due to the need to use anhydrous alcoholic feedstocks, which contributes significantly to the cost of advanced biofuel production. Isobutanol formation with pre-catalyst trans-[RuCl2(dppm)2] (1) has been shown to be tolerant to the addition of water to the system, achieving an isobutanol yield of 36% at 78% selectivity with water concentrations typical of that of a crude fermentation broth. Key to this success is both the catalyst's tolerance to water itself and the use of a hydroxide rather than an alkoxide base; other catalysts explored are less effective with hydroxides. Alcoholic drinks have also been used as surrogates for the fermentation broth: the use of lager as the ethanol source yielded 29% isobutanol at 85% selectivity in the liquid phase.
- Pellow, Katy J.,Wingad, Richard L.,Wass, Duncan F.
-
-
Read Online
- Inverse Bimetallic RuSn Catalyst for Selective Carboxylic Acid Reduction
-
Inverse bimetallic catalysts (IBCs), synthesized by sequential deposition of noble and oxophilic metals, offer potential reactivity enhancements to various reactions, including the reduction of carboxylic acids for renewable fuels and chemicals. Here, we demonstrate that an IBC comprising RuSn exhibits high selectivity for propionic acid reduction to 1-propanol, while Ru alone results in cracking. On RuSn, X-ray absorption spectroscopy identified Ru0 nanoparticles with a near-surface bimetallic Ru0Sn0 alloy and small SnOx domains. Corresponding model surfaces were examined with density functional theory to elucidate the observed selectivity difference. Only selective hydrogenation is predicted to be favorable on SnOx/Ru, with the SnOx clusters facilitating C-OH scission and Ru enabling hydrogen activation. Intrinsic barriers along nonselective pathways suggest that the RuSn alloy and SnOx resist cracking. SnOx/Ru hydrogenation activity was supported experimentally by inhibiting hydrogenation with phenylphosphonic acid, differentiating the system from fully alloyed RuSn metallic nanoparticles. Overall, this work demonstrates a plausible mechanism for selective reduction of carboxylic acids and proposes a roadmap for rational design of IBCs.
- Vorotnikov, Vassili,Eaton, Todd R.,Settle, Amy E.,Orton, Kellene,Wegener, Evan C.,Yang, Ce,Miller, Jeffrey T.,Beckham, Gregg T.,Vardon, Derek R.
-
-
Read Online
- Peptide-modified dendrimers as templates for the production of highly reactive catalytic nanomaterials
-
Peptide-driven nanomaterials synthesis and assembly has become a significant research thrust due to the capability to generate a range of multifunctional materials with high spatial precision and tunable properties. Despite the extensive amount of available literature, the majority of studies report the use of free peptides to drive synthesis and assembly. Such strategies are not an entirely accurate representation of nature, as many materials binding peptides found in biological systems are sterically constrained to a larger biological motif. Herein we report the synthesis of catalytic Pd nanomaterials using constrained peptides covalently attached to the surface of small, water-soluble dendrimers. Using the R5 peptide conjugated to polyamidoamine dendrimer as a bioconjugate, Pd nanomaterials were generated that displayed altered morphologies compared to nanomaterials templated with free R5. It was discovered that the peptide surface density on the dendrimer affected the resulting nanoscale morphology. Furthermore, the catalytic activities of Pd materials templated with R5/dendrimer are higher as compared to the R5-templated Pd materials for the hydrogenation of allyl alcohol, with an average increase in turnover frequency of ～1500 mol product (mol Pd × h)-1. Small angle X-ray scattering analysis and dynamic light scattering indicate that Pd derived from R5/dendrimer templates remained less aggregated in solution and displayed more available reactive Pd surface area. Such morphological changes in solution are attributed to the constrained peptide binding motifs, which altered the Pd morphology and subsequent properties. Moreover, the results of this study suggest that constrained materials binding peptide systems can be employed as a means to alter morphology and improve resulting properties.
- Bedford, Nicholas M.,Bhandari, Rohit,Slocik, Joseph M.,Seifert, Soenke,Naik, Rajesh R.,Knecht, Marc R.
-
-
Read Online
- Size-selective hydrogenation of olefins by Dendrimer-encapsulated palladium nanoparticles
-
Nearly monodisperse (1.7 ± 0.2 nm) palladium nanoparticles were prepared within the interiors of three different generations of hydroxyl-terminated poly(amidoamine) (PAMAM) dendrimers. These dendrimer-encapsulated catalysts (DECs) were used to hydrogenate allyl alcohol and four α-substituted derivatives in a 4:1 methanol/water mixture. The results indicate that steric crowding on the dendrimer periphery, which increases with dendrimer generation, can act as an adjustable-mesh nanofilter. That is, by controlling the packing density on the dendrimer periphery, it is possible to control access of substrates to the encapsulated catalytic nanoparticle. In general, higher-generation DECs or larger substrates resulted in lower turnover frequencies (although some interesting exceptions were noted). Although the main products of the olefin hydrogenation reactions were the corresponding alkanes, ketones were also obtained when monosubstituted α-olefins were used as substrates. NMR spectroscopy was used to measure the size selectivity of DECs for the competitive hydrogenation of allyl alcohol and 3-methyl-1-penten-3-ol. The effect on catalytic rate as a function of nanoparticle size is also briefly discussed.
- Niu,Yeung,Crooks
-
-
Read Online
- HOMOGENEOUS HYDROGENATION OF ALDEHYDES TO ALCOHOLS WITH RUTHENIUM COMPLEX CATALYSTS
-
A number of ruthenium complexes catalyse the reduction of aldehydes to their corresponding alcohols in toluene solution under mild reaction conditions.The most convenient catalyst precursor is hydridochlorocarbonyltris(triphenylphosphine)ruthenium(II).Turnover numbers up to 32 000 have been achieved with this catalyst.The rate of hydrogenation is first order with respect to the substrate concentration, the catalyst concentration and the hydrogen pressure, and is also affected by acid and basic additives.
- Sanchez-Delgado, R.A.,Andriollo, A.,Ochoa, O.L. De,Suarez, T.,Valencia, N.
-
-
Read Online
- Catalytic conversion of methanol/ethanol to isobutanol - A highly selective route to an advanced biofuel
-
Catalysts based on ruthenium diphosphine complexes convert methanol/ethanol mixtures to the advanced biofuel isobutanol, with extremely high selectivity (>99%) at good (>75%) conversion via a Guerbet-type mechanism.
- Wingad, Richard L.,Bergstr?m, Emilie J. E.,Everett, Matthew,Pellow, Katy J.,Wass, Duncan F.
-
-
Read Online
- Nanoconfinement Engineering over Hollow Multi-Shell Structured Copper towards Efficient Electrocatalytical C?C coupling
-
Nanoconfinement provides a promising solution to promote electrocatalytic C?C coupling, by dramatically altering the diffusion kinetics to ensure a high local concentration of C1 intermediates for carbon dimerization. Herein, under the guidance of finite-element method simulations results, a series of Cu2O hollow multi-shell structures (HoMSs) with tunable shell numbers were synthesized via Ostwald ripening. When applied in CO2 electroreduction (CO2RR), the in situ formed Cu HoMSs showed a positive correlation between shell numbers and selectivity for C2+ products, reaching a maximum C2+ Faradaic efficiency of 77.0±0.3 % at a conversion rate of 513.7±0.7 mA cm?2 in a neutral electrolyte. Mechanistic studies clarified the confinement effect of HoMSs that superposition of Cu shells leads to a higher coverage of localized CO adsorbate inside the cavity for enhanced dimerization. This work provides valuable insights for the delicate design of efficient C?C coupling catalysts.
- Li, Jiawei,Liu, Chunxiao,Xia, Chuan,Xue, Weiqing,Zeng, Jie,Zhang, Menglu,Zheng, Tingting
-
supporting information
(2021/12/06)
-
- A Heterogeneous Pt-ReOx/C Catalyst for Making Renewable Adipates in One Step from Sugar Acids
-
Renewable adipic acid is a value-added chemical for the production of bioderived nylon. Here, the one-step conversion of mucic acid to adipates was achieved in high yield through deoxydehydration (DODH) and catalytic transfer hydrogenation (CTH) by a bifunctional Pt-ReOx/C heterogeneous catalyst with isopropanol as solvent and reductant. The Pt-ReOx/C catalyst is reusable and was regenerated at least five times. The catalyst exhibits a broad substrate scope of various diols. Spectroscopic studies of Pt-ReOx/C revealed ReVII and Pt0 as the relevant species for DODH and CTH, respectively. Isotope labeling experiments support a monohydride mechanism for CTH over Pt. This work demonstrates a reusable bifunctional catalyst for a one-step valorization of sugar acids to a practical monomer, which opens the door to multifunctional catalysis streamlining valorization of biomass-derived molecules.
- Jang, Jun Hee,Ro, Insoo,Christopher, Phillip,Abu-Omar, Mahdi M.
-
-
- MOF-derived hcp-Co nanoparticles encapsulated in ultrathin graphene for carboxylic acids hydrogenation to alcohols
-
Highly efficient conversion of carboxylic acids to valuable alcohols is a great challenge for easily corroded non-noble metal catalysts. Here, a series of few-layer graphene encapsulated metastable hexagonal closed-packed (hcp) Co nanoparticles were fabricated by reductive pyrolysis of metal-organic framework precursor. The sample pyrolyzed at 400 °C (hcp-Co@G400) presented outstanding performance and stability for converting a variety of functional carboxylic acids and its turnover frequency was one magnitude higher than that of conventional facc-centered cubic (fcc) Co catalysts. In situ DRIFTS spectroscopy of model reaction acetic acid hydrogenation and DFT calculation results confirm that carboxylic acid initially undergoes dehydroxylation to RCH2CO* followed by consecutive hydrogenation to RCH2CH2OH through RCH2COH*. Acetic acid prefers to vertically adsorb at hcp-Co (0 0 2) facet with a much lower adsorption energy than parallel adsorption at fcc-Co (1 1 1) surface, which plays a key role in decreasing the activation barrier of the rate-determining step of acetic acid dehydroxylation.
- Dong, Mei,Fan, Weibin,Gao, Xiaoqing,Zhu, Shanhui
-
p. 201 - 211
(2021/06/03)
-
- METHOD FOR PRODUCING BIO ALCOHOL FROM INTERMEDIATE PRODUCTS OF ANAEROBIC DIGESTION TANK
-
The present invention relates to a method for producing a bio-alcohol by reacting a mixture of volatile fatty acid with methanol in 2 through 11 in a reactor in the presence of a 280 °C-membered alkaline earth metal catalyst or 400 °C transition metal catalyst formed based on a support.
- -
-
Paragraph 0057-0060; 0063; 0065-0066; 0068-0069; 0071
(2021/05/25)
-
- Synthesis, crystal and structural characterization, Hirshfeld surface analysis and DFT calculations of three symmetrical and asymmetrical phosphonium salts
-
Three stable phosphonium salts of 1,4-butanediylebis(triphenylphosphonium) dibromide I, butane-4?bromo-1-(triphenylphosphonium) bromide II and 1,3-propanediylbis(triphenylphosphonium) tetrahydroborate III were synthesized and structurally characterized. Single crystal X-ray diffraction analysis, spectroscopic methods and thermal analysis methods were used for the characterization of titled compounds. Crystallographic data showed that compound I crystallized in the triclinic crystal system with Pī space group and compound II crystallized in the monoclinic crystal system with P21/c space group. The crystal packing structures of I and II were stabilized by various intermolecular interactions, especially of C–H···π contacts. The molecular Hirshfeld surface analysis and 2D fingerprint revealed that the C···H contacts have 24.3% and 18.4% contributions in the crystal packings of compounds I and II, respectively. In addition, the H···Br (28.5%) contact has a considerable contribution to the crystal architecture of compound II. Theoretical studies were performed by DFT method to investigate the structural properties of the titled compounds. The isotopic ratio of boron in tetrahydroborate anion of compound III calculated by 1H NMR spectroscopy. The isotopic ratio for 10B/11B was 19.099 / 80.900%. Reduction of some carbonyl compounds to corresponding alcohols was performed by compound III and the optimum conditions were determined.
- Delaram, Behnaz,Gholizadeh, Mostafa,Makari, Faezeh,Nokhbeh, Seyed Reza,Salimi, Alireza
-
-
- Disproportionation of aliphatic and aromatic aldehydes through Cannizzaro, Tishchenko, and Meerwein–Ponndorf–Verley reactions
-
Disproportionation of aldehydes through Cannizzaro, Tishchenko, and Meerwein–Ponndorf–Verley reactions often requires the application of high temperatures, equimolar or excess quantities of strong bases, and is mostly limited to the aldehydes with no CH2 or CH3 adjacent to the carbonyl group. Herein, we developed an efficient, mild, and multifunctional catalytic system consisting AlCl3/Et3N in CH2Cl2, that can selectively convert a wide range of not only aliphatic, but also aromatic aldehydes to the corresponding alcohols, acids, and dimerized esters at room temperature, and in high yields, without formation of the side products that are generally observed. We have also shown that higher AlCl3 content favors the reaction towards Cannizzaro reaction, yet lower content favors Tishchenko reaction. Moreover, the presence of hydride donor alcohols in the reaction mixture completely directs the reaction towards the Meerwein–Ponndorf–Verley reaction. Graphic abstract: [Figure not available: see fulltext.].
- Sharifi, Sina,Sharifi, Hannah,Koza, Darrell,Aminkhani, Ali
-
p. 803 - 808
(2021/07/20)
-
- SELECTIVE PRODUCTION OF METHANOL AND ETHANOL FROM CO HYDROGENATION
-
A method for producing methanol and ethanol is disclosed. The method can include contacting a gaseous stream comprising carbon monoxide (CO) and hydrogen (H22) with a crystalline cobalt molybdenum catalyst under conditions suitable to produce a products stream comprising methanol and ethanol from the CO and H22.
- -
-
Paragraph 0036-0037
(2021/02/12)
-
- Sulfate-functionalized metal-organic frameworks supporting Pd nanoparticles for the hydrogenolysis of glycerol to 1,2-propanediol
-
Selective hydrogenolysis of glycerol to 1,2-propanediol is one of the options for the chemical utilization of glycerol. In this work, we synthesized sulfate-functionalized metal-organic frameworks loading palladium nanoparticles, MOF-808-SO4-Pd, as effective glycerol hydrogenolysis catalysts. The sulfate groups are responsible for the dehydration of glycerol. Subsequently, palladium nanoparticles hydrogenate the intermediates to 1,2-propanediol. The synergistic reaction between acid sites and Pd gave 93.9% selectivity of 1,2-propanediol with a reaction rate of 22.4 mmol gPd-1 h-1. Our work highlights new opportunities in using acid-functionalized MOFs as novel supports for metal nanoparticle catalysts for dual site catalysis.
- Cao, Yonghua,He, Xuefeng,Li, Zhe,Wang, Cheng,Zhang, Jingzheng
-
p. 21263 - 21269
(2021/12/09)
-
- One-pot reduction-hydrophobization of heterogenized platinum with 1,1,3,3-tetramethyldisiloxane
-
An original approach for the design of hydrophobized heterogeneous platinum-based catalytic systems is reported here. Heterogenization was performed by depositing the platinum precursor (H2PtCl6) on macroporous styrene-divinylbenzene (SDVB) beads with a high surface area, -330 m2?g?1, as determined by N2 sorption data, followed by treating with 1,1,3,3-tetramethyldisiloxane (TMDS) as Pt(IV) reducing agent without the need of special conditions. Simultaneously, the coupling by Si-O-Si bonds of the TMDS oxidation or hydrolysis intermediates endowed the SDVB-Pt systems with an enhanced hydrophobicity (up to 10 times higher than that of SDVB support). In addition, to obtain an optimum catalytic system, which stabilize the supported platinium against leaching, several mixtures of TMDS with other methylsiloxane precursors, namely, methyltrimethoxysilane (MTMS), (Formula presented.)-bis(trimethylsiloxy)poly(dimethylsiloxane-H-methylsiloxane) (PDMHS), and (Formula presented.)-bis(trimethylsiloxy)poly(dimethylsiloxane-co-vinylmethylsiloxane) (PDMVS), have been systematically investigated. The reduction of platinum, visible by an instant change in the color from yellow to black, was confirmed by X-ray photoelectron spectroscopy analysis, while its total content in the samples was determined quantitatively by atomic absorption spectroscopy. The obtained systems have been preliminarily assessed for catalytic activity in the hydrosilylation of 1,3-bis(vinyl)tetramethyldisiloxane and allyl alcohol with TMDS, and 1-hexene with trimethoxysilane, as model reactions. The results indicate the high suitability of these systems as catalysts for the selective anti-Markovnikov hydrosilylation of alkenes, as well as for the very fast oxidation-condensation homocoupling of H-silanes in presence of a green oxidation agent (air), under mild conditions, with the release of hydrogen and its in situ addition to the double bond.
- Baltag, Laurentiu,Cazacu, Maria,Damoc, Madalin,Dinu, Maria Valentina,Ionita, Gheorghe,Macsim, Ana-Maria,Nicolescu, Alina,Stoica, Alexandru-Constantin
-
-
- Hydrogenolysis of glycerol to 1,3-propanediol over H-ZSM-5-supported iridium and rhenium oxide catalysts
-
The hydrogenolysis of glycerol to 1,3-propanediol (1,3-PrD) over Ir-ReOx catalysts supported on H-ZSM-5 (denoted as Ir-ReOx/H-ZSM-5) was investigated. The glycerol conversion and 1,3-PrD yield strongly depended on the catalyst composition (Re/Ir) and the amount of metal loading. The analyses of the catalysts using X-ray powder diffraction and transmission electron microscopy revealed that a higher metal dispersion of Ir and a smaller Ir particle were encouraged by the addition of Re to the catalyst. Furthermore, a strong electronic interaction between Ir and Re in the Ir-ReOx/H-ZSM-5 catalyst was observed from X-ray photoelectron spectroscopy measurements. In the study on the effects of operating conditions, increasing the temperature and reaction time resulted in a higher glycerol conversion at the expense of 1,3-PrD selectivity due to over-hydrogenolysis, whereas increasing the pressure had a positive effect on 1,3-PrD selectivity. The highest 1,3-PrD yield observed was achieved at 2.8% with 14.9% glycerol conversion and 19.0% 1,3-PrD selectivity.
- Chanklang, Sarun,Chareonpanich, Metta,Faungnawakij, Kajornsak,Mondach, Wongsaphat,Seubsai, Anusorn,Somchuea, Pooripong,Witoon, Thongthai
-
-
- Hydrogenolysis of glycerol in an aqueous medium over Pt/WO3/zirconium phosphate catalysts studied by1H NMR spectroscopy
-
Bifunctional Pt/WO3/zirconium phosphate catalyzes the liquid-phase hydrogenolysis of glycerol in an aqueous medium.1H NMR spectroscopy (solvent suppression pulse program) is employed to monitor this reaction. Propanediols (1,3 + 1,2-PDO) formed as the major product along with propanols (1- and 2-POs) as the minor product. A synergistic enhancement in glycerol conversion and selectivity to 1,3-PDO was observed when both Pt and WO3were present in the catalyst. Avolcano-shapevariation of catalytic activity with W content was observed. A catalyst with 8 wt% W and 1 wt% Pt exhibited the highest selective hydrogenolysis performance (glycerol conversion = 92.3% and total PDOs selectivity = 45.9% and 1,3-PDO selectivity = 20.8% at 200 °C). Dispersed Pt in contact with polytungstate-type WO3species was found to be the active catalytic site.1H NMR spectroscopy is demonstrated as an attractive technique toquantifythe products of a glycerol hydrogenolysis reaction.
- Bhowmik, Susmita,Enjamuri, Nagasuresh,Darbha, Srinivas
-
p. 5013 - 5022
(2021/03/26)
-
- Facilitating Pt?WOx Species Interaction for Efficient Glycerol Hydrogenolysis to 1,3-Propanediol
-
Designing efficient catalysts for glycerol hydrogenolysis to 1,3-propanediol (1,3-PDO), which involves the selective cleavage of the secondary C?O bond, is a challenging task. Current Pt?WOx-based catalysts often provide low atom efficiency of W and Pt toward 1,3-PDO production due to undesired catalyst structures. Herein, we fabricate the highly-dispersed substantially uniform WOx species on inert α-Al2O3 support by simple high-temperature heat-treatment, and the amount of Pt?WOx interface active sites could be adjusted by Pt loading, showing an excellent catalytic performance in glycerol hydrogenolysis at high concentration of glycerol, especially the unprecedented W efficiency (76 g1,3-PDOgW?1 h?1) toward 1,3-PDO. The high catalytic efficiency is attributed to the strong interaction between the isolated WO4 species and platinum, which could in-situ generate the Br?nsted acid sites during the reaction as evidenced by IR analysis with NH3 adsorption.
- Zhao, Binbin,Liang, Yu,Liu, Lei,He, Qian,Dong, Jin-Xiang
-
p. 3695 - 3705
(2021/07/02)
-
- Citric acid modified Ni3P as a catalyst for aqueous phase reforming and hydrogenolysis of glycerol to 1,2-PDO
-
Citric acid (CA) modified Ni3P catalysts with small particle sizes were prepared by H2 temperature-programmed reduction (H2-TPR) of the precursors, which were prepared by co-precipitation with Ni(NO3)2·6H2O and (NH4)2HPO4, using citric acid as the chelating agent and calcining under a N2 atmosphere. The catalytic activity of the prepared catalysts was tested in the aqueous phase reforming (APR) and hydrogenolysis of glycerol to 1,2-propanediol (1,2-PDO). The effects of the CA/Ni molar ratio and reaction conditions (temperature, pressure, and time) on APR and hydrogenolysis of glycerol were investigated. The CA(1)-Ni3P catalyst exhibited the best performance at 220 °C, 0.5 MPa N2, and 8 h with 74.6% glycerol conversion and 43.2% selectivity of 1,2-PDO. The prepared CA(x)-Ni3P catalysts were characterized by XRD, N2 adsorption, Raman spectroscopy, CO-chemisorption and TEM. The addition of CA significantly enhanced the dispersion of Ni species in the precursors and enlarged the surface area of the catalyst. The residual carbonaceous species after calcination in N2 prevented the aggregation of Ni3P particles and promoted the reduction of the precursors. Compared with the unmodified Ni3P and CA(x)-Ni3P calcined in air, the CA(x)-Ni3P calcined in N2 with a smaller average particle size exhibited higher catalytic activities.
- Hu, Tianyu,Liu, Bingyu,Liu, Shan,Liu, Ying-Ya,Sun, Zhichao,Wang, Anjie,Wang, Yao,Yu, Zhiquan
-
p. 21725 - 21731
(2021/12/13)
-
- Interworking ligand, hydroformylation catalyst and preparation method of dihydric alcohol
-
The invention discloses an interworking ligand, a hydroformylation catalyst and a preparation method of dihydric alcohol. The interworking ligand comprises a ligand unit I and a ligand unit II, has the characteristics of a bidentate phosphine ligand, and is high in catalytic activity and good in stability; and when the catalyst is used for preparing dihydric alcohol from olefin, linear alcohol can be obtained through a one-step method, and the content of by-products in a traditional series process is reduced. The method has the advantages of simple and convenient process, low cost and energy consumption, good production safety, high product quality and the like, and is particularly suitable for large-scale industrial production.
- -
-
Paragraph 0051; 0059-0060; 0095-0096; 0097-0098
(2021/07/09)
-
- Hydrodeoxygenation of C4-C6 sugar alcohols to diols or mono-alcohols with the retention of the carbon chain over a silica-supported tungsten oxide-modified platinum catalyst
-
The hydrodeoxygenation of erythritol, xylitol, and sorbitol was investigated over a Pt-WOx/SiO2 (4 wt% Pt, W/Pt = 0.25, molar ratio) catalyst. 1,4-Butanediol can be selectively produced with 51% yield (carbon based) by erythritol hydrodeoxygenation at 413 K, based on the selectivity over this catalyst toward the regioselective removal of the C-O bond in the -O-C-CH2OH structure. Because the catalyst is also active in the hydrodeoxygenation of other polyols to some extent but much less active in that of mono-alcohols, at higher temperature (453 K), mono-alcohols can be produced from sugar alcohols. A good total yield (59%) of pentanols can be obtained from xylitol, which is mainly converted to C2 + C3 products in the literature hydrogenolysis systems. It can be applied to the hydrodeoxygenation of other sugar alcohols to mono-alcohols with high yields as well, such as erythritol to butanols (74%) and sorbitol to hexanols (59%) with very small amounts of C-C bond cleavage products. The active site is suggested to be the Pt-WOx interfacial site, which is supported by the reaction and characterization results (TEM and XAFS). WOx/SiO2 selectively catalyzed the dehydration of xylitol to 1,4-anhydroxylitol, whereas Pt-WOx/SiO2 promoted the transformation of xylitol to pentanols with 1,3,5-pentanetriol as the main intermediate. Pre-calcination of the reused catalyst at 573 K is important to prevent coke formation and to improve the reusability.
- Betchaku, Mii,Cao, Ji,Liu, Lujie,Nakagawa, Yoshinao,Tamura, Masazumi,Tomishige, Keiichi,Yabushita, Mizuho
-
p. 5665 - 5679
(2021/08/16)
-
- Cu boosting the collaborative effect of Ni and H+in alloyed NiCu/saponite catalysts for hydrogenolysis of glycidol
-
The effect of copper on various acid saponite supported Ni-Cu bimetallic catalysts, prepared with different Ni?:?Cu ratios, was studied for the liquid phase hydrogenolysis of glycidol on a batch reactor at 393 and 453 K. Characterization of the catalysts showed that Ni and Cu are in close contact as the XRD measurements evidenced the formation of an alloy. H2chemisorption results revealed that the measured metallic area progressively decreased with an increase in the wt% of copper. In the presence of high metal activity (higher Ni wt%), the formation of 1,2-propanediol (1,2-PD) outweighed, while acid activity led to the formation of dimerization and oligomerization products. The addition of Cu and the increase of the reaction temperature decreased the diol formation but boosted the 1,3-PD/1,2-PD ratio. This could be explained by an improvement of the collaborative effect between the metal Ni and the H+of the saponite. Therefore, the presence of an appropriate amount of Cu allowed the control of the hydrogenation capacity of Ni and enhanced the collaborative effect of Ni and H+favouring the formation of 1,3-propanediol with respect to 1,2-propanediol.
- Cesteros, Yolanda,Gebretsadik, Fiseha Bogale,González, María Dolores,Ruiz-Martinez, Javier,Salagre, Pilar
-
p. 9198 - 9207
(2021/07/12)
-
- Size-Dependent Activity and Selectivity of Atomic-Level Copper Nanoclusters during CO/CO2 Electroreduction
-
As a favorite descriptor, the size effect of Cu-based catalysts has been regularly utilized for activity and selectivity regulation toward CO2/CO electroreduction reactions (CO2/CORR). However, little progress has been made in regulating the size of Cu nanoclusters at the atomic level. Herein, the size-gradient Cu catalysts from single atoms (SAs) to subnanometric clusters (SCs, 0.5–1 nm) to nanoclusters (NCs, 1–1.5 nm) on graphdiyne matrix are readily prepared via an acetylenic-bond-directed site-trapping approach. Electrocatalytic measurements show a significant size effect in both the activity and selectivity toward CO2/CORR. Increasing the size of Cu nanoclusters will improve catalytic activity and selectivity toward C2+ productions in CORR. A high C2+ conversion rate of 312 mA cm?2 with the Faradaic efficiency of 91.2 % are achieved at ?1.0 V versus reversible hydrogen electrode (RHE) over Cu NCs. The activity/selectivity-size relations provide a clear understanding of mechanisms in the CO2/CORR at the atomic level.
- Duan, Lele,Hu, Junhui,Ji, Yongfei,Long, Baihua,Rong, Weifeng,Wei, Shuting,Xi, Shibo,Zang, Wenjie,Zou, Haiyuan
-
supporting information
p. 466 - 472
(2020/10/29)
-
- Conversion of succinic acid over Ni and Co catalysts
-
Liquid-phase hydrogenation of succinic acid (SA) over supported Ni and Co catalysts was investigated at 200 °C and 6 MPa of H2. Reduced and passivated catalysts with the same surface metal density (2.5 atoms of metal per nm2 of support) were prepared by incipient wetness impregnation. The catalysts were characterized by X-ray diffraction (XRD), N2 adsorption, X-ray photoelectron spectroscopy (XPS), temperature-programmed reduction (TPR), CO-chemisorption, and temperature-programmed desorption of NH3 (TPD-NH3). The Ni and Co catalysts supported over SiO2 showed different product distribution, due to the adsorption of the SA over the surface of catalysts, determined by DFT calculations. The Co/SiO2, Co/SiO2-Al2O3, and Co/Al2O3 catalysts showed different product distribution, which was correlated with total acidity from TPD-NH3 results. In general, the Co catalysts promoted the hydrogenation process; however, the highest total acidity showed by Co/Al2O3 also promoted the dehydration process. Finally, the initial rate follows the trend according to the dispersion determined by CO-chemisorption.
- Rojas, Mabel,Zarate, Ximena,Canales, Roberto I.,Dongil, Ana Belen,Pazo, Cesar,Saavedra-Torres, Mario,Escalona, Néstor
-
p. 165 - 176
(2020/05/14)
-
- CO hydrogenation over K-Co-MoSx catalyst to mixed alcohols: A kinetic analysis
-
Higher alcohol synthesis (HAS) from syngas is one of the most promising approaches to produce fuels and chemicals. Our recent investigation on HAS showed that potassium-promoted cobalt-molybdenum sulfide is an effective catalyst system. In this study, the intrinsic kinetics of the reaction were studied using this catalyst system under realistic conditions. The study revealed the major oxygenated products are linear alcohols up to butanol and methane is the main hydrocarbon. The higher alcohol products (C3+) followed an Anderson-Schultz-Flory distribution while the catalyst suppressed methanol and ethanol formation. The optimum reaction conditions were estimated to be at temperature of 340°C, pressure of 117?bar, gas hourly space velocity of 27?000?mL?g–1h–1 and H2/CO molar feed ratio of 1. A kinetic network has been considered and kinetic parameters were estimated by nonlinear regression of the experimental data. The results indicated an increasing apparent activation energy of alcohols with the length of alcohols except for ethanol. The lower apparent activation energy of alcohols compared with hydrocarbon evidenced the efficiency of this catalyst system to facilitate the formation of higher alcohols.
- Negahdar, Leila,Xi, Xiaoying,Zeng, Feng,Winkelman,Heeres, Hero Jan,Palkovits, Regina
-
supporting information
p. 419 - 427
(2020/11/30)
-
- Coupling of Cu(100) and (110) Facets Promotes Carbon Dioxide Conversion to Hydrocarbons and Alcohols
-
Copper can efficiently electro-catalyze carbon dioxide reduction to C2+ products (C2H4, C2H5OH, n-propanol). However, the correlation between the activity and active sites remains ambiguous, impeding further improvements in their performance. The facet effect of copper crystals to promote CO adsorption and C?C coupling and consequently yield a superior selectivity for C2+ products is described. We achieve a high Faradaic efficiency (FE) of 87 % and a large partial current density of 217 mA cm?2 toward C2+ products on Cu(OH)2-D at only ?0.54 V versus the reversible hydrogen electrode in a flow-cell electrolyzer. With further coupled to a Si solar cell, record-high solar conversion efficiencies of 4.47 % and 6.4 % are achieved for C2H4 and C2+ products, respectively. This study provides an in-depth understanding of the selective formation of C2+ products on Cu and paves the way for the practical application of electrocatalytic or solar-driven CO2 reduction.
- Zhong, Dazhong,Zhao, Zhi-Jian,Zhao, Qiang,Cheng, Dongfang,Liu, Bin,Zhang, Gong,Deng, Wanyu,Dong, Hao,Zhang, Lei,Li, Jingkun,Li, Jinping,Gong, Jinlong
-
supporting information
p. 4879 - 4885
(2021/01/20)
-
- High-Rate CO2 Electroreduction to C2+ Products over a Copper-Copper Iodide Catalyst
-
Electrochemical CO2 reduction reaction (CO2RR) to multicarbon hydrocarbon and oxygenate (C2+) products with high energy density and wide availability is of great importance, as it provides a promising way to achieve the renewable energy storage and close the carbon cycle. Herein we design a Cu-CuI composite catalyst with abundant Cu0/Cu+ interfaces by physically mixing Cu nanoparticles and CuI powders. The composite catalyst achieves a remarkable C2+ partial current density of 591 mA cm?2 at ?1.0 V vs. reversible hydrogen electrode in a flow cell, substantially higher than Cu (329 mA cm?2) and CuI (96 mA cm?2) counterparts. Induced by alkaline electrolyte and applied potential, the Cu-CuI composite catalyst undergoes significant reconstruction under CO2RR conditions. The high-rate C2+ production over Cu-CuI is ascribed to the presence of residual Cu+ and adsorbed iodine species which improve CO adsorption and facilitate C?C coupling.
- Li, Hefei,Liu, Tianfu,Wei, Pengfei,Lin, Long,Gao, Dunfeng,Wang, Guoxiong,Bao, Xinhe
-
supporting information
p. 14329 - 14333
(2021/05/19)
-
- PROCESS FOR ISOBUTANOL PRODUCTION FROM ETHANOL AND SYNGAS
-
Processes for converting ethanol and syngas (CO and H2) to isobutanol are disclosed. Syngas and ethanol are reacted in the first reaction zone in the presence of a first heterogeneous catalyst to produce a first reactor effluent comprising a first mixture of alcohols. The first reactor effluent is reacted a second reaction zone in the presence of a second heterogeneous catalyst to produce a second reactor effluent comprising a second mixture of alcohols. The second reactor effluent is separated into an overhead gas stream and a liquid bottom stream. The liquid bottom stream is separated into at least a C1-2 stream, a C3 stream, and a C4+ stream. The isobutanol is recovered from the C4+ stream.
- -
-
Page/Page column 10
(2021/04/01)
-
- Machine-Learning-Guided Discovery and Optimization of Additives in Preparing Cu Catalysts for CO2Reduction
-
Discovery and optimization of new catalysts can be potentially accelerated by efficient data analysis using machine-learning (ML). In this paper, we record the process of searching for additives in the electrochemical deposition of Cu catalysts for CO2 reduction (CO2RR) using ML, which includes three iterative cycles: "experimental test; ML analysis; prediction and redesign". Cu catalysts are known for CO2RR to obtain a range of products including C1 (CO, HCOOH, CH4, CH3OH) and C2+ (C2H4, C2H6, C2H5OH, C3H7OH). Subtle changes in morphology and surface structure of the catalysts caused by additives in catalyst preparation can lead to dramatic shifts in CO2RR selectivity. After several ML cycles, we obtained catalysts selective for CO, HCOOH, and C2+ products. This catalyst discovery process highlights the potential of ML to accelerate material development by efficiently extracting information from a limited number of experimental data.
- Guo, Ying,He, Xinru,Su, Yuming,Dai, Yiheng,Xie, Mingcan,Yang, Shuangli,Chen, Jiawei,Wang, Kun,Zhou, Da,Wang, Cheng
-
supporting information
p. 5755 - 5762
(2021/05/07)
-
- The Hydrodeoxygenation of Glycerol over NiMoSx: Catalyst Stability and Activity at Hydropyrolysis Conditions
-
Catalytic activity tests were run to elucidate the chemistry and catalyst stability for the hydrodeoxygenation of glycerol and other aliphatic oxygenates over a NiMoSx/Al2O3 catalyst at different pretreatments at hydropyrolysis conditions in a continuous flow reactor. Reactivity metrics were developed to quantify and compare the reactivity of NiMo for deoxygenation, hydrogenation, and C?C cleavage. Activity experiments showed sulfided NiMo and reduced NiMo catalysts had similar deoxygenation and hydrogenation activity for glycerol HDO at 400 °C and 270 psig H2 with the NiMoSx catalyst showing higher C?C cleavage activity. Without a sulfur co-feed, both the NiMoSx and NiMoOx catalysts lost >40 % deoxygenation activity over 30 h time on stream. With a 2100 ppm H2S co-feed the NiMoSx catalyst showed a 12 times decrease in the deactivation rate for deoxygenation and 6 time decrease in the deactivation rate for hydrogenation. The main products at high conversion were propylene, propane, ethylene, methane, CO, methanol, ethanol, and 1-propanol. At low conversion, the major products were unsaturated allyl alcohol, acrolein, hydroxyacetone, and acetaldehyde. With no H2S co-feed at short contact times, there was a significant amount of carbon loss possibly due to condensation reactions, while at 2100 ppm H2S in the feed, the carbon balance was 102.4 %. Temperature programmed oxidation of the spent NiMoSx catalysts after 30 h of glycerol HDO without an H2S co-feed showed that one of the causes of deactivation was coking.
- Anderson, Anthony D.,Lanci, Michael P.,Buchanan, J. Scott,Dumesic, James A.,Huber, George W.
-
p. 425 - 437
(2020/11/30)
-
- Carbon monoxide and hydrogen (syngas) as a C1-building block for selective catalytic methylation
-
A catalytic reaction using syngas (CO/H2) as feedstock for the selective β-methylation of alcohols was developed whereby carbon monoxide acts as a C1 source and hydrogen gas as a reducing agent. The overall transformation occurs through an intricate network of metal-catalyzed and base-mediated reactions. The molecular complex [Mn(CO)2Br[HN(C2H4PiPr2)2]]1comprising earth-abundant manganese acts as the metal component in the catalytic system enabling the generation of formaldehyde from syngas in a synthetically useful reaction. This new syngas conversion opens pathways to install methyl branches at sp3carbon centers utilizing renewable feedstocks and energy for the synthesis of biologically active compounds, fine chemicals, and advanced biofuels.
- Kaithal, Akash,H?lscher, Markus,Leitner, Walter
-
p. 976 - 982
(2021/02/06)
-
- Operando Investigation of Ag-Decorated Cu2O Nanocube Catalysts with Enhanced CO2 Electroreduction toward Liquid Products
-
Direct conversion of carbon dioxide into multicarbon liquid fuels by the CO2 electrochemical reduction reaction (CO2RR) can contribute to the decarbonization of the global economy. Here, well-defined Cu2O nanocubes (NCs, 35 nm) uniformly covered with Ag nanoparticles (5 nm) were synthesized. When compared to bare Cu2O NCs, the catalyst with 5 at % Ag on Cu2O NCs displayed a two-fold increase in the Faradaic efficiency for C2+ liquid products (30 % at ?1.0 VRHE), including ethanol, 1-propanol, and acetaldehyde, while formate and hydrogen were suppressed. Operando X-ray absorption spectroscopy revealed the partial reduction of Cu2O during CO2RR, accompanied by a reaction-driven redispersion of Ag on the CuOx NCs. Data from operando surface-enhanced Raman spectroscopy further uncovered significant variations in the CO binding to Cu, which were assigned to Ag?Cu sites formed during CO2RR that appear crucial for the C?C coupling and the enhanced yield of liquid products.
- Herzog, Antonia,Bergmann, Arno,Jeon, Hyo Sang,Timoshenko, Janis,Kühl, Stefanie,Rettenmaier, Clara,Lopez Luna, Mauricio,Haase, Felix T.,Roldan Cuenya, Beatriz
-
supporting information
p. 7426 - 7435
(2021/02/26)
-
- B-Cu-Zn Gas Diffusion Electrodes for CO2 Electroreduction to C2+ Products at High Current Densities
-
Electroreduction of CO2 to multi-carbon products has attracted considerable attention as it provides an avenue to high-density renewable energy storage. However, the selectivity and stability under high current densities are rarely reported. Herein, B-doped Cu (B-Cu) and B-Cu-Zn gas diffusion electrodes (GDE) were developed for highly selective and stable CO2 conversion to C2+ products at industrially relevant current densities. The B-Cu GDE exhibited a high Faradaic efficiency of 79 % for C2+ products formation at a current density of ?200 mA cm?2 and a potential of ?0.45 V vs. RHE. The long-term stability for C2+ formation was substantially improved by incorporating an optimal amount of Zn. Operando Raman spectra confirm the retained Cu+ species under CO2 reduction conditions and the lower overpotential for *OCO formation upon incorporation of Zn, which lead to the excellent conversion of CO2 to C2+ products on B-Cu-Zn GDEs.
- Song, Yanfang,Junqueira, Jo?o R. C.,Sikdar, Nivedita,?hl, Denis,Dieckh?fer, Stefan,Quast, Thomas,Seisel, Sabine,Masa, Justus,Andronescu, Corina,Schuhmann, Wolfgang
-
supporting information
p. 9135 - 9141
(2021/03/16)
-
- Role of Ga3+promoter in the direct synthesis of iso-butanolviasyngas over a K-ZnO/ZnCr2O4catalyst
-
The direct synthesis of iso-butanol is an important reaction in syngas (composed of CO and H2) conversion. K-ZnO/ZnCr2O4(K-ZnCr) is a commonly used catalyst. Here, Ga3+is used as an effective promoter to boost the efficiency of the catalyst and retard the production of CO2. X-ray diffraction, X-ray photoelectron spectroscopy, ultraviolet-visible diffuse reflection spectroscopy and electron microscopy were used to characterize the structural variations with different amounts of Ga3+, the results showed that the particle size of the catalyst decreases with the addition of Ga3+. The temperature-programmed desorption of NH3and CO2, and diffuse reflectance infrared Fourier-transform spectroscopy (DRIFTs) analysis of the CO adsorption revealed that the acidity and basicity were altered owing to the different forms of Ga3+adoption. X-ray photoelectron spectroscopy and density functional theory (DFT) calculations revealed that the formation of Ga clusters that are coordinated on the exposed surfaces of ZnCr2O4, and undergo a tetra-coordinated Ga3+exchange with one of the Zn in ZnCr2O4(ZG) and ZnGa2O4, probably depends on the amount of Ga added. The structural evolution of the Ga3+promoted K-ZnO/ZnCr2O4catalysts can be described as follows: (i) the main forms are ZG and Ga coordinated ZnCr2O4, in which the amount of Ga3+is below 1.10 wt%; and (ii) the Ga3+containing compound is gradually changed from ZG to ZnGa2O4and the amount of gallium clusters increased when the amount of Ga3+was higher than 1.10 wt%. The catalytic performance evaluation results show that K-Ga1.10ZnCr exhibits the highest space time yield and selectivity of alcohols, in which the three compounds play different roles in syngas conversion: ZG is the main active site that boosts the efficiency of the catalysts, owing to the intensified CO adsorption and decreased activation energy of CHO formation through CO hydrogenation; ZnGa2O4only modifies the surface basicity and acidity on the catalyst, thereby impacting the carbon chain growth after the CO is adsorbed. The effects of Ga coordinated with ZnCr2O4shows little impact on the CO adsorption owing to the weak electron donating effects of Ga.
- Zhang, Tao,Zeng, Chunyang,Wu, Yingquan,Gong, Nana,Yang, Jiaqian,Yang, Guohui,Tsubaki, Noritatsu,Tan, Yisheng
-
p. 1077 - 1088
(2021/02/26)
-
- Dehydrogenative alcohol coupling and one-pot cross metathesis/dehydrogenative coupling reactions of alcohols using Hoveyda-Grubbs catalysts
-
In this study,in situformed ruthenium hydride species that were generated from Grubbs type catalysts are used as efficient catalysts for dehydrogenative alcohol coupling and sequential cross-metathesis/dehydrogenative coupling reactions. The selectivity of Grubbs first generation catalysts (G1) in dehydrogenative alcohol coupling reactions can be tuned for the ester formation in the presence of weak bases, while the selectivity can be switched to the β-alkylated alcohol formation using strong bases. The performance of Hoveyda-Grubbs 2nd generation catalyst (HG2) was improved in the presence of tricyclohexylphosphine for the selective synthesis of ester derivatives with weak and strong bases in quantitative yields. Allyl alcohol was used as self and cross-metathesis substrate for the HG2 catalyzed sequential cross-metathesis/dehydrogenative alcohol coupling reactions to obtain γ-butyrolactone and long-chain ester derivatives in quantitative yields.
- ?zer, Halenur,Arslan, Dilan,?ztürk, Bengi ?zgün
-
p. 5992 - 6000
(2021/04/12)
-
- Chromium-Catalyzed Production of Diols From Olefins
-
Processes for converting an olefin reactant into a diol compound are disclosed, and these processes include the steps of contacting the olefin reactant and a supported chromium catalyst comprising chromium in a hexavalent oxidation state to reduce at least a portion of the supported chromium catalyst to form a reduced chromium catalyst, and hydrolyzing the reduced chromium catalyst to form a reaction product comprising the diol compound. While being contacted, the olefin reactant and the supported chromium catalyst can be irradiated with a light beam at a wavelength in the UV-visible spectrum. Optionally, these processes can further comprise a step of calcining at least a portion of the reduced chromium catalyst to regenerate the supported chromium catalyst.
- -
-
Paragraph 0111
(2021/03/19)
-
- High-Pressure CO Electroreduction at Silver Produces Ethanol and Propanol
-
Reducing CO2 to long-chain carbon products is attractive considering such products are typically more valuable than shorter ones. However, the best electrocatalyst for making such products from CO2, copper, lacks selectivity. By stud
- Corbett, Paul J.,Koper, Marc T. M.,Raaijman, Stefan J.,Schellekens, Maarten P.
-
supporting information
p. 21732 - 21736
(2021/08/26)
-
- Ultrastable Cu Catalyst for CO2 Electroreduction to Multicarbon Liquid Fuels by Tuning C–C Coupling with CuTi Subsurface
-
Production of multicarbon (C2+) liquid fuels is a challenging task for electrocatalytic CO2 reduction, mainly limited by the stabilization of reaction intermediates and their subsequent C?C couplings. In this work, we report a unique catalyst, the coordinatively unsaturated Cu sites on amorphous CuTi alloy (a-CuTi@Cu) toward electrocatalytic CO2 reduction to multicarbon (C2-4) liquid fuels. Remarkably, the electrocatalyst yields ethanol, acetone, and n-butanol as major products with a total C2-4 faradaic efficiency of about 49 % at ?0.8 V vs. reversible hydrogen electrode (RHE), which can be maintained for at least 3 months. Theoretical simulations and in situ characterization reveals that subsurface Ti atoms can increase the electron density of surface Cu sites and enhance the adsorption of *CO intermediate, which in turn reduces the energy barriers required for *CO dimerization and trimerization.
- Duan, Chongxiong,Duan, Delong,Hu, Fei,Jiang, Jun,Jiang, Yawen,Kong, Tingting,Liu, Qi,Long, Ran,Lv, Xuefeng,Wang, Xiaonong,Xiong, Yujie,Yang, Li,Zeng, Longjiao
-
supporting information
p. 26122 - 26127
(2021/11/12)
-
- The site pair matching of a tandem Au/CuO-CuO nanocatalyst for promoting the selective electrolysis of CO2to C2products
-
Tandem catalysis, in which a CO2-to-C2 process is divided into a CO2-to-CO/?CO step and a CO/?CO-to-C2 step, is promising for enhancing the C2 product selectivity when using Cu-based electrochemical CO2 reduction catalysts. In this work, a nanoporous hollow Au/CuO-CuO tandem catalyst was used for catalyzing the eCO2RR, which exhibited a C2 product FE of 52.8% at -1.0 V vs. RHE and a C2 product partial current density of 78.77 mA cm-2 at -1.5 V vs. RHE. In addition, the C2 product FE stably remained at over 40% over a wide potential range, from -1.0 V to -1.5 V. This superior performance was attributed to good matching in terms of the optimal working potential and charge-transfer resistance between CO/?CO-production sites (Au/CuO) and CO/?CO-reduction sites (CuO). This site pair matching effect ensured sufficient supplies of CO/?CO and electrons at CuO sites at the working potentials, thus dramatically enhancing the formation rate of C2 products. This journal is
- Sun, Xiao-Chen,Yin, Hai-Jing,Yuan, Chen-Yue,Yuan, Kun,Zhang, Ya-Wen,Zheng, Ya-Li,Zhou, Jun-Hao
-
p. 38486 - 38494
(2021/12/20)
-
- Single-atom Ru catalyst for selective synthesis of 3-pentanone: Via ethylene hydroformylation
-
A Ru single-atom (Ru SA) catalyst supported on activated carbon was adopted to synthesize 3-pentanone with 83.3% selectivity via heterogeneous ethylene hydroformylation, while 52.1% ethane selectivity was obtained for Ru nanoparticles (Ru NPs). The atomically dispersed Ru species with oxidation state (Ruδ+) and Ru-C4O coordination structure were identified as the active sites for efficient C-C coupling to generate 3-pentanone, while metallic Ru nanoparticles exhibited high activity for ethylene hydrogenation to ethane. Density functional theory (DFT) calculation revealed that the energy barrier of the direct coupling of C2H5CO? with C2H5? to form 3-pentanone on Ru SA was much lower than that on Ru NPs. As a result, the formation of 3-pentanone over Ru SA was more favourable than propanal, which was admittedly generated via coupling of C2H5CO? and H?. This strategy may provide a potential green route for the one-pot synthesis of 3-pentanone with high atomic economy.
- Dang, Yaru,Jiang, Zheng,Li, Shenggang,Li, Xiao,Lin, Tiejun,Mei, Bingbao,Qin, Tingting,Sun, Yuhan,Tang, Zhiyong,Wu, Bo,Zhong, Liangshu
-
supporting information
p. 9038 - 9047
(2021/11/30)
-
- Regulating Hydrogenation Chemoselectivity of α,β-Unsaturated Aldehydes by Combination of Transfer and Catalytic Hydrogenation
-
Two hydrogenation mechanisms, transfer and catalytic hydrogenation, were combined to achieve higher regulation of hydrogenation chemoselectivity of cinnamyl aldehydes. Transfer hydrogenation with ammonia borane exclusively reduced C=O bonds to get cinnamyl alcohol, and Pt-loaded metal–organic layers efficiently hydrogenated C=C bonds to synthesize phenyl propanol with almost 100 % conversion rate. The hydrogenation could be performed under mild conditions without external high-pressure hydrogen and was applicable to various α,β-unsaturated aldehydes.
- Zhou, Yangyang,Li, Zihao,Liu, Yanbo,Huo, Jia,Chen, Chen,Li, Qiling,Niu, Songyang,Wang, Shuangyin
-
p. 1746 - 1750
(2020/02/25)
-
- METHOD FOR PRODUCING ALCOHOL
-
PROBLEM TO BE SOLVED: To provide a method for producing selectively alcohol from carboxylic acid under mild conditions. SOLUTION: In the presence of a catalyst with M1 and M2 as metal species supported on a support, a substrate is reduced to produce a corresponding alcohol. (M1 is Rh, Pt, Ru, Ir, or Pd; M2 is Sn, V, Mo, W, or Re; the support is ZrO2, hydroxyapatite, Nb2O5, fluoroapatite, or hydrotalcite; the substrate is the formula 1a, 1b, or 1c). SELECTED DRAWING: None COPYRIGHT: (C)2020,JPO&INPIT
- -
-
Paragraph 0101-0112
(2020/11/26)
-
- A tannin-derived zirconium-containing porous hybrid for efficient Meerwein-Ponndorf-Verley reduction under mild conditions
-
Both the use of renewable natural sources to prepare catalytic materials and the Meerwein-Ponndorf-Verley (MPV) reduction for carbonyl compounds are very attractive topics in catalysis. In this study, tannins were simply assembled with zirconium in water for the scalable preparation of a heterogeneous zirconium-tannin hybrid catalyst (Zr-tannin). Various characterizations demonstrated the formation of robust porous inorganic-organic frameworks and strong Lewis acid-base sites in Zr-tannin. The cooperative effect of these acid-base sites and the abundant porosity endowed Zr-tannin with a remarkable catalytic performance for the MPV reduction of a broad range of carbonyl compounds to alcohols with 2-propanol under mild conditions. Moreover, Zr-tannin exhibited good recyclability for at least five reaction cycles. This novel strategy using tannins as the raw materials to construct heterogeneous catalytic materials may have a huge potential for green chemical synthesis due to low cost, nontoxicity, and sustainability.
- Leng, Yan,Shi, Langchen,Du, Shengyu,Jiang, Jiusheng,Jiang, Pingping
-
p. 180 - 186
(2020/01/13)
-
- One-pot synthesis of 1,3-butanediol by 1,4-anhydroerythritol hydrogenolysis over a tungsten-modified platinum on silica catalyst
-
Chemical production of 1,3-butanediol from biomass-derived compounds was first reported by 1,4-anhydroerythritol hydrogenolysis over a Pt-WOx/SiO2 catalyst. The reaction proceeded by ring opening hydrogenolysis of 1,4-anhydroerythritol followed by selective removal of secondary OH groups in 1,2,3-butanetriol, and an overall 1,3-butanediol yield up to 54% was then obtained. The performance of the Pt-WOx/SiO2 catalyst for 1,4-anhydroerythritol hydrogenolysis was closely correlated with that for glycerol hydrogenolysis to 1,3-propanediol. The optimized Pt-WOx/SiO2 (Pt: 4 wt% and W: 0.94 wt%) catalyst showed 57% yield of 1,3-propanediol.
- Asano, Takehiro,Liu, Lujie,Nakagawa, Yoshinao,Tamura, Masazumi,Tomishige, Keiichi
-
supporting information
p. 2375 - 2380
(2020/05/14)
-
- Highly Active, Selective, and Recyclable Water-Soluble Glutathione-Stabilized Pd and Pd-Alloy Nanoparticle Catalysts in Biphasic Solvent
-
Glutathione-protected Pd, PdAu and PdPt nanoparticles (NPs) show greatly increased reactivity and stability towards the hydrogenation/isomerization of allyl alcohol in a biphasic organic/aqueous solvent mixture compared to single-phase alkanethiol-protected Pd-based NPs. NPs synthesized under aerobic conditions have higher activity compared to those synthesized under nitrogen, with the highest TOF of 676 mole product/mole metal/hour for 75 : 25 PdAu NPs at 20 mL/min H2 flow. 75 : 25 PdAu NPs prepared under nitrogen have a maximum TOF of 507 at 20 mL/min H2 flow, but can be recycled 4 times (9 times at 8 mL/min H2 flow). Ethyl acetate is a better organic phase solvent compared to dichloromethane and chlorobenzene in terms of TOF and recyclability. All of the NPs studied show >80 % selectivity for the isomer product (propanal). The branched, open structure of the glutathione and use of the biphasic solvent provides high catalytic activity, high selectivity, and easy removal of the products in the organic phase for good recyclability of the water-soluble catalysts.
- Bhama, Shekhar,Sibakoti, Tirtha R.,Jasinski, Jacek B.,Zamborini, Francis P.
-
p. 2253 - 2261
(2020/03/13)
-
- Electrocatalytic CO2 Reduction on CuOx Nanocubes: Tracking the Evolution of Chemical State, Geometric Structure, and Catalytic Selectivity using Operando Spectroscopy
-
The direct electrochemical conversion of carbon dioxide (CO2) into multi-carbon (C2+) products still faces fundamental and technological challenges. While facet-controlled and oxide-derived Cu materials have been touted as promising catalysts, their stability has remained problematic and poorly understood. Herein we uncover changes in the chemical and morphological state of supported and unsupported Cu2O nanocubes during operation in low-current H-Cells and in high-current gas diffusion electrodes (GDEs) using neutral pH buffer conditions. While unsupported nanocubes achieved a sustained C2+ Faradaic efficiency of around 60 % for 40 h, the dispersion on a carbon support sharply shifted the selectivity pattern towards C1 products. Operando XAS and time-resolved electron microscopy revealed the degradation of the cubic shape and, in the presence of a carbon support, the formation of small Cu-seeds during the surprisingly slow reduction of bulk Cu2O. The initially (100)-rich facet structure has presumably no controlling role on the catalytic selectivity, whereas the oxide-derived generation of under-coordinated lattice defects, can support the high C2+ product yields.
- Gliech, Manuel,Jovanov, Zarko,M?ller, Tim,Roldan Cuenya, Beatriz,Scholten, Fabian,Sinev, Ilya,Strasser, Peter,Thanh, Trung Ngo,Timoshenko, Janis,Varela, Ana Sofia,Wang, Xingli
-
supporting information
p. 17974 - 17983
(2020/08/19)
-
- Understanding the deactivation behavior of Pt/WO3/Al2O3 catalyst in the glycerol hydrogenolysis reaction
-
The selective hydrogenolysis of glycerol to 1,3-propanediol is a highly important reaction for both improving the profitability of biodiesel and valorization of biomass. While intensive research efforts have been devoted to enhancing the catalytic activity and selectivity, little is focused on the stability although the latter is of paramount importance to practical applications. In this work, we investigated the stability of Pt/WO3/Al2O3 and observed a continuous deactivation trend during a 700 h time-on-stream run. Neither the leaching of active W nor the coking was responsible for the deactivation. Instead, XRD, HAADF-STEM and CO chemisorption results clearly showed the occurrence of significant aggregation of Pt particles, which caused a remarkable decrease of Pt-WOx interfacial sites. As a consequence, strong Br?nsted acid sites which were in situ formed by H2 dissociation at the Pt-WOx interfacial sites were reduced, leading to the deactivation of the catalyst.
- Lei, Nian,Liu, Fei,Miao, Zhili,Pan, Xiaoli,Wang, Aiqin,Wang, Hua,Zhang, Tao
-
p. 1261 - 1267
(2020/03/13)
-
- Discovering positively charged Pt for enhanced hydrogenolysis of glycerol to 1,3-propanediol
-
Atomically-dispersed Pt supported on WOx-modified tantalum oxide was developed as a highly active catalyst for selective hydrogenolysis of glycerol, with the productivity of 30.80 g gPt-1 h-1 toward 1,3-propanediol. The WOx species pre-deposited on T-Ta2O5 were found to assist the atomic dispersion of platinum. The WOx-stabilized Ptδ+ species adsorb hydrogen easily and facilitate the hydrogen heterolytic dissociation, which significantly enhances the capability of in situ generated Br?nsted acid sites and the hydrogenation activity. This provides a new strategy for developing bi-functional catalysts for a broad range of hydrogen and acid-involved reaction.
- Zhao, Binbin,Liang, Yu,Liu, Lei,He, Qian,Dong, Jinxiang
-
supporting information
p. 8254 - 8259
(2020/12/31)
-
- Hydrodeoxygenation of glycerol into propanols over a Ni/WO3–TiO2 catalyst
-
Hydrodeoxygenation of glycerol in a flow reactor over a bifunctional Ni/WO3–TiO2 catalyst at 240–255 °C and hydrogen pressure of 3 MPa affords propan-1-ol and propan-2-ol in total yield of 94%.
- Greish, Alexander A.,Finashina, Elena D.,Tkachenko, Olga P.,Nikul'shin, Pavel A.,Ershov, Mikhail A.,Kustov, Leonid M.
-
p. 119 - 120
(2020/03/03)
-
- Reduction of Propanoic Acid over Pd-Promoted Supported WOx Catalysts
-
Silica-, titania-, and zirconia-supported tungsten oxide catalysts were synthesized by wetness impregnation techniques. When promoted with Pd, these materials catalyzed the reduction of propanoic acid to 1-propanol at 433 K with a selectivity of up to 92 % (13.5 % conversion) in atmospheric pressure of H2. Over Pd-promoted WOx/TiO2, the observed orders of reaction were 0.2 in H2 and 0.7 in propanoic acid, and the apparent activation energy was 54 kJ mol?1. In situ X-ray absorption spectroscopy of Pd-promoted WOx/SiO2 revealed a slight reduction of the W from +6 to an average oxidation state of about +5 during H2 treatment above 473 K. In situ infrared spectroscopy indicated the catalyst surface was covered mostly by propanoate species during reaction. For comparison, supported phosphotungstic acid was also evaluated as a catalyst under identical conditions, but the resulting high acidity of the catalyst was deleterious to alcohol selectivity.
- Kammert, James D.,Brezicki, Gordon,Miyake, Naomi,Stavitski, Eli,Davis, Robert J.
-
p. 314 - 325
(2019/11/28)
-
- Highly Selective Production of Ethylene by the Electroreduction of Carbon Monoxide
-
Conversion of carbon monoxide to high value-added ethylene with high selectivity by traditional syngas conversion process is challenging because of the limitation of Anderson-Schulz–Flory distribution. Herein we report a direct electrocatalytic process for highly selective ethylene production from CO reduction with water over Cu catalysts at room temperature and ambient pressure. An unprecedented 52.7 % Faradaic efficiency of ethylene formation is achieved through optimization of cathode structure to facilitate CO diffusion at the surface of the electrode and Cu catalysts to enhance the C?C bond coupling. The highly selective ethylene production is almost without other carbon-based byproducts (e.g. C1–C4 hydrocarbons and CO2) and avoids the drawbacks of the traditional Fischer–Tropsch process that always delivers undesired products. This study provides a new and promising strategy for highly selective production of ethylene from the abundant industrial CO.
- Chen, Ruixue,Su, Hai-Yan,Liu, Deyu,Huang, Rui,Meng, Xianguang,Cui, Xiaoju,Tian, Zhong-Qun,Zhang, Dong H.,Deng, Dehui
-
supporting information
p. 154 - 160
(2019/12/15)
-
- New strategy for production of primary alcohols from aliphatic olefins by tandem cross-metathesis/hydrogenation
-
Primary alcohols are widely used in industry as solvents and precursors of detergents. The classic methods for hydration of terminal alkenes always produce the Markovnikov products. Herein, we reported a reliable approach to produce primary alcohols from terminal alkenes combining with biomass-derived allyl alcohol by tandem cross-metathesis/hydrogenation. A series of primary alcohol with different chain lengths was successfully produced in high yields (ca. 90percent). Computational studies revealed that self-metathesis and hydrogenation of substrates are accessible but much slower than cross-metathesis. This new methodology represents a unique alternative to primary alcohols from terminal alkenes.
- Jia, Ruilong,Zuo, Zhijun,Li, Xu,Liu, Lei,Dong, Jinxiang
-
supporting information
p. 1525 - 1529
(2019/11/11)
-
- Effect of Promoter Nature on Synthesis Gas Conversion to Alcohols over (K)MeMoS2/Al2O3 Catalysts
-
The influence of the promoter nature and of a modifier in (K)(Me)MoS2/Al2O3 (Me=Fe, Co, Ni) catalysts on the conversion and selectivity of products of synthesis gas conversion to alcohols and jnl oxygenates was investigated. Relationships between promoter nature, hydrocarbon chain length and selectivity in the formed alcohols were established. Electronic structure of a promoter atom in an active site (AS) was found to strongly affect selectivity of alcohol formation. Promotion of the S-edge by Fe, Co or Ni suppressed hydrogen activation, which resulted in a lower synthesis gas conversion. Promotion of the M-edge by Fe, Co, or Ni entailed the formation of double vacancies which are active sites of synthesis gas conversion. Potassium affected the oxophilicity of Mo atoms and reduced Co/Ni-promoted MoS AS. It decreased the probability of C?O bond breaking in the adsorbed intermediate and shifted selectivity from the formation of alkyl towards alkoxide fragments over these catalysts.
- Maximov, Vladimir V.,Permyakov, Eugenii A.,Dorokhov, Viktor S.,Wang, Anjie,Kooyman, Patricia J.,Kogan, Victor M.
-
p. 1443 - 1452
(2020/02/11)
-
- Investigating the Origin of Enhanced C2+Selectivity in Oxide-/Hydroxide-Derived Copper Electrodes during CO2Electroreduction
-
Oxide-/hydroxide-derived copper electrodes exhibit excellent selectivity toward C2+ products during the electrocatalytic CO2 reduction reaction (CO2RR). However, the origin of such enhanced selectivity remains controversial. Here, we prepared two Cu-based electrodes with mixed oxidation states, namely, HQ-Cu (containing Cu, Cu2O, CuO) and AN-Cu (containing Cu, Cu(OH)2). We extracted an ultrathin specimen from the electrodes using a focused ion beam to investigate the distribution and evolution of various Cu species by electron microscopy and electron energy loss spectroscopy. We found that at the steady stage of the CO2RR, the electrodes have all been reduced to Cu0, regardless of the initial states, suggesting that the high C2+ selectivities are not associated with specific oxidation states of Cu. We verified this conclusion by control experiments in which HQ-Cu and AN-Cu were pretreated to fully reduce oxides/hydroxides to Cu0, and the pretreated electrodes showed even higher C2+ selectivity compared with their unpretreated counterparts. We observed that the oxide/hydroxide crystals in HQ-Cu and AN-Cu were fragmented into nanosized irregular Cu grains under the applied negative potentials. Such a fragmentation process, which is the consequence of an oxidation-reduction cycle and does not occur in electropolished Cu, not only built an intricate network of grain boundaries but also exposed a variety of high-index facets. These two features greatly facilitated the C-C coupling, thus accounting for the enhanced C2+ selectivity. Our work demonstrates that the use of advanced characterization techniques enables investigating the structural and chemical states of electrodes in unprecedented detail to gain new insights into a widely studied system.
- Lei, Qiong,Zhu, Hui,Song, Kepeng,Wei, Nini,Liu, Lingmei,Zhang, Daliang,Yin, Jun,Dong, Xinglong,Yao, Kexin,Wang, Ning,Li, Xinghua,Davaasuren, Bambar,Wang, Jianjian,Han, Yu
-
p. 4213 - 4222
(2020/03/04)
-
- Mechanistic Insights into Electroreductive C-C Coupling between CO and Acetaldehyde into Multicarbon Products
-
Production of valuable multicarbon (C3+) products through the electrochemical CO2 and CO reduction reactions (CO2RR and CORR) is desirable; however, mechanistic understanding that enables C-C coupling beyond the self-coupling of CO to valuable products is lacking. In this work, we elucidate the C-C coupling mechanism between CO and acetaldehyde, a reactive intermediate in both CO2RR and CORR, via combined isotopic labeling and in situ spectroscopic investigations. CO attacks the carbonyl carbon of acetaldehyde in the coupling, and the carbon in CO ends up in the hydroxymethyl group (-CH2OH) of the produced 1-propanol. While the coupling between CO and acetaldehyde does occur when the CORR is conducted with added acetaldehyde, only a minor fraction (up to 36%) of 1-propanol is from this pathway, and the majority of it is produced in the CORR by the self-coupling among CO. The adsorbed methylcarbonyl is proposed as the likely intermediate where the reaction pathway bifurcates to C2 and C3 products; i.e., it could either be hydrogenated to acetaldehyde and ethanol or couple with CO leading to the formation of 1-propanol.
- Chang, Xiaoxia,Malkani, Arnav,Xu, Bingjun,Yang, Xuan
-
p. 2975 - 2983
(2020/03/10)
-
